Generally, in an image process for converting color image data to monochrome (single color) image data, monochrome image data are generated based on brightness component information such as the luminance, the brightness, and the density of the color image data. However, in a color image, it sometimes becomes difficult to discriminate the parts that can be discriminated by the differences in the color feature quantity (hereinafter referred to as color information), such as hue and saturation, even when the difference in the brightness component (for example, brightness difference) is small by converting into a monochrome image.
Conventionally, as an image process device for solving this type of problem, there was an image process device provided with means for extracting first and second objects that are different from each other from the color image data, means for determining whether or not drawing positions of the first and second objects overlap, and brightness control means for controlling the brightness difference between the first and second objects after the monochromatic conversion so that the brightness difference becomes a predetermined value or more when the drawing positions of the first and second objects overlap (for example, see Patent Document 1).